Ice maker with piezo dielectric elastomer sensor

ABSTRACT

An ice maker includes, among other things, an ice cube mold, an ice cube remover and a force sensor comprising a piezo dielectric elastomer (PDE). The ice cube mold has at least one cavity for receiving liquid. The ice cube remover is configured to apply a removal force to either the mold or an ice cube. The force sensor is provided on either the mold or the remover and provides an output indicative of the removal force. Upon the removal of an ice cube from the cavity, the ice cube remover applies a removal force to the mold or the ice cube to effect the removal of the ice cube from the cavity and the force sensor outputs a signal indicative of the removal force.

CROSS-REFERENCE TO RELATED APPLICATION

This Application represents a divisional application of and claimspriority to U.S. patent application Ser. No. 14/476,796 entitled “IceMaker with Piezo Dielectric Elastomer Sensor”, filed Sep. 4, 2014,currently allowed, and further claims priority to and the benefit ofU.S. Provisional Patent Application Ser. No. 61/873,911, filed on Sep.5, 2013, the entire disclosures of which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

The freezer compartment of a residential refrigerator may include anautomatic ice maker. An ice maker typically includes an ice mold forreceiving water and forming ice cubes while the water freezes. Once themolded ice cubes are frozen, a motor either twists the ice mold orrotates an arm to eject the ice cubes out of the mold. The ejected icecubes may then collect in a bin until dispensed from the freezercompartment.

SUMMARY OF THE INVENTION

The invention relates to an ice maker comprising: an ice cube moldhaving at least one cavity for receiving liquid; an ice cube removerconfigured to apply a removal force to at least one of the mold and icecube; a force sensor comprising a piezo dielectric elastomer (PDE)provided on one of the mold and remover and providing an outputindicative of the removal force; wherein upon the removal of an ice cubefrom the cavity, the ice cube remover applies a removal force to one ofthe mold and ice cube to effect the removal of the ice cube from thecavity and the force sensor outputs a signal indicative of the removalforce.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a front view of a refrigerator with an ice maker according toan embodiment of the invention.

FIG. 2 is a front view of an ice maker that twists an ice cube mold toremove ice cubes according to an embodiment of the invention.

FIG. 3 is an overhead view of an ice cube mold for an ice maker with aforce sensor positioned along the side edge of the mold according to anembodiment of the invention.

FIG. 4 is an overhead view of an ice cube mold for an ice maker with aforce sensor positioned between cavities of the mold according to anembodiment of the invention.

FIG. 5 is a front view of an ice maker that twists a rake to remove icecubes from an ice cube mold according to an embodiment of the invention.

FIG. 6 is side view of a rake for ice cube removal with a force sensorpositioned along the shaft of the rake according to an embodiment of theinvention.

FIG. 7 is a side view of a rake for ice cube removal with an array offorce sensors positioned along the fingers of the rake according to anembodiment of the invention.

FIG. 8 shows a side view of a portion of refrigerator with a door havinga ledge on which the ice storage bin may rest according to an embodimentof the invention.

FIG. 9 is a front view of an ice bucket in contact with a force sensorfor determining the weight of the ice in the bucket according to anembodiment of the invention.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Three basic configurations of refrigerators with a freezer compartmentinclude a side-by-side configuration, a top freezer configuration and abottom freezer configuration. As shown in FIG. 1, a refrigerator 10 in aside-by-side configuration has a freezer compartment 12 located next toa refrigerated compartment 14. By contrast, a top freezer configurationhas a freezer compartment located above the refrigerated compartment andthe bottom freezer configuration has a freezer compartment locatedbeneath the refrigerated compartment. Generally, an ice maker 16 and anice storage bin 22 are located in the freezer compartment 12 of therefrigerator 10. However, hybrid combinations of the basicconfigurations may include a French door configuration where the icemaker 16 may be included in the refrigerated compartment.

The ice maker 16 may mount to the wall 18 of the freezer compartment 12.Alternatively, the ice maker 16 may mount to the door 20 of the freezercompartment 12 or attach to a base 24 that in turn may mount to the wall18 or door 20 of the freezer compartment 12. The ice storage bin 22 isconfigured to receive and then store ice ejected from the ice maker 16and may be positioned on the door 20 or beneath the ice maker 16 in thefreezer compartment 12.

Referring now to FIG. 2, the ice maker 16 may further include an icecube mold 100 for receiving water and forming ice cubes, a motor 102 fordelivering torque to remove the ice cubes during the ice harvestingprocess and a controller 104. The controller 104 may control aspects ofthe ice harvesting process including when and to what level applicationof motor torque to remove ice cubes is required. The ice maker 16 may beconfigured as a twist ice maker to remove ice cubes by twisting the icecube mold 100. Alternatively, as described below, the ice maker may beconfigured to remove ice cubes by rotating the fingers of a rake throughthe portions of the ice cube mold containing the ice cubes.

Referring now to FIG. 3, an ice cube mold 100 for a twist ice maker witha force sensor 112 positioned along the side edge 114 of the ice cubemold 100 may now be described. The ice cube mold 100 may have one ormore cavities 116 for receiving liquid. For a twist ice maker, the icecube mold 100 may be rotatably mounted to a drive mechanism that mayapply a removal force to the ice cubes in the flexible ice cube mold100. For example, the ice cube mold 100 of a twist ice maker may besupported for rotation about a longitudinal axis 118 by a drivercoupling 120 at one end 122 of the mold and a suitable shaft 124 at theopposite end 126 of the mold. An automatically controlled motor 102 maybe configured to apply a torque to the driver coupling 120 to effectrotation.

During an ice harvesting operation, rotation of one end 122 of the icecube mold 100 without concurrent rotation of the opposite end 126 mayeffect a twisting of the ice cube mold 100 to a level that freespreviously formed ice cubes in the cavities 116. When the ice cube mold100 reaches a sufficient angle of twist to effect full ice extraction,an element 128, such as a boss located on the ice cube mold 100, mayactivate a momentary switch by physical contact. The element 128 may belocated at any point on the ice cube mold 100 where the deflection ofthe element 128 correlates to the overall twisting of the ice cube mold100. For example, as shown in FIG. 3, the element 128 may be placedalong the end 122 of the mold nearest to the driver coupling 120, thoughother positions on the mold may be used.

Automatic ice makers do not typically include a feedback mechanism tocontrol the amount of torque generated by the motor 102 for extractingice cubes from the ice cube mold 100. Excess friction between one ormore of the ice cubes and the cavities 116 in the ice cube mold 100 mayprevent an ice cube from ejecting from the ice cube mold 100 without theaddition of more force. Consequently, elements of the ice maker that aresubject to the application of the additional force may experiencefatigue and failure.

To provide feedback indicative of the level of force being applied tovarious elements of the ice maker, particularly to the elements actuatedduring an ice cube harvesting operation, a sensor 112 capable ofoutputting an electrical signal indicative of an applied mechanicalforce may be provided. Generally, sensors that convert mechanical forceinto electrical signals are known as electromechanical transducers. Aforce sensor for elements of an ice maker may be subject to large anglesof deflection and high values of strain. Namely, a sufficient angle oftwist for an ice cube mold to induce a level of torsion that will ejectice cubes typically ranges from 20 to 40 degrees. Due to these operatingcharacteristics, a particularly relevant type of electromechanicaltransducer for use as a force sensor is a piezo dielectric elastomer(PDE).

PDEs are a type of dielectric electroactive polymer (DEP). Generally,DEPs are materials in which actuation is caused by electrostatic forcesbetween two electrodes which squeeze the polymer. PDEs are capable ofvery high strains and are fundamentally a capacitor that changescapacitance when a voltage is applied by allowing the polymer tocompress in thickness and expand in area in response to an electricfield. DEPs require no power to keep the actuator at a given position.Because of the highly flexible nature of DEP, PDEs may be used assensors for measuring an applied force in an environment wheresignificant deformation may occur that would render conventionaltransducers inoperative.

With the use of PDE force sensors, the applied motor torque may bemonitored and managed in a controlled fashion to aid in the iceharvesting process. As shown in FIG. 3, implementing a PDE as a forcesensor 112 on the ice cube mold 100 may provide a feedback mechanism forthe controller 104 to detect excessive twisting of the ice cube mold 100and prevent early fatigue. The force sensor 112 may induce a voltage inresponse to the degree of deformation of the ice cube mold 10 along thearea of the ice cube mold 10 in contact with the force sensor 112.Placing the force sensor 112 in an area where the ice cube mold 100 hasan elevated risk of fracturing may provide actionable feedback fordetermining when a particular area of the ice cube mold 100 isexcessively twisted. Therefore, conventional actuation of a momentaryswitch may provide a measure of detection for achieving sufficient twistto release the ice cubes and the PDE force sensor 112 may provide anadditional measure to help prevent excessive twisting in a specific areaprone to fatigue.

While the force sensor 112 as shown in FIG. 3 is placed along the sideedge 114 of the ice cube mold 100 proximal to the driver coupling 120and orthogonal to the longitudinal axis 118, other configurations arecontemplated. Non-uniform deformation of the ice cube mold 100 inresponse to an applied removal force may result from a number of diversecauses that may have different effects on different areas of the icecube mold 100. For example, calcium deposits forming on the ice cubemold 100 may cause the ice cubes to stick inside the ice cube mold 100during the ice harvesting process. However, the extent to which the icecubes stick may vary between cavities 116 resulting in variable levelsof strain between each cavity 116. Consequently, as shown in FIG. 4, thePDE force sensor 130 may be placed between two of the cavities 116.Multiple twist sensors 112 may be implemented for monitoring multiplehigh risk areas. For example, a force sensor 112 may be placed betweeneach pair of cavities 116. Alternatively, the PDE force sensor 112 maybe oriented at an angle relative to the longitudinal axis 118.Preferably, the force sensor 112 may be located at any position andorientation on the ice cube mold 100 where excessive twisting may occuras a result of a non-uniform deformation of the ice cube mold 100.

The ice cube mold 100 may be formed of any material that is bothflexible and has a thermal conductivity conducive to forming ice. Forexample, aluminum has a thermal conductivity much higher than water andtherefore aids in producing ice quickly. Other materials contemplatedfor the ice cube mold generally include plastics and metals. Thematerial used for the ice cube mold and its corresponding properties maydirectly affect the preferred placement of the one or more forcesensors. Other factors may include the shape and relative placement ofthe cavities of the ice cube mold 100.

Referring now to FIG. 5, as an alternative to twisting the ice cube mold100, the ice maker 16 previously described in FIG. 2 may further includea rake 200 whereby the controller 104 may direct the motor 102 to rotatethe rake 200. To expel ice cubes from the ice cube mold 100, each finger212 of the rake 200 is rotatable through a cavity 116 of the ice cubemold 100.

As seen in FIG. 6, the rake 200 may further include a rotatable shaft210 and at least one finger 212 extending from the shaft 210. Therotatable shaft 210 may be coupled to the motor 202 such that torque maybe applied to the shaft 210 to effect rotation during an ice harvestingprocess.

During an ice harvesting process with a rotating rake 200, a heatingelement connected to the ice cube mold 100 may apply heat to thecavities 116. Then, the rake 200 may rotate the fingers 212 through thebriefly heated cavities 116 and effect removal of the ice cubes. Similarto the twisting of the ice cube mold 100, the process of rotating thefingers 212 of the rake 200 through the cavities 116 may apply anexcessive level of force to the ice cubes causing either the ice cubesto break or elements of the rake 200 to fatigue. Additionally,undesirable levels of noise may occur during the ice harvesting process.By implementing a PDE force sensor 214 on the rake 200 in a mannersimilar to that described above for the ice cube mold 100, a controlledapplication of torque from the motor 102 to rotate the rake 200 maymitigate deleterious effects including broken ice, rake fatigue andexcess noise.

For example, as shown in FIG. 6, placing the PDE force sensor 214directly on the rotatable shaft 210 of the rake 200, the applied motorforce may be monitored and limited until the bond between the ice cubesand the cavities 116 is broken. In this way, a more gentle ice harvestmay mitigate the previously described negative effects. While the PDEforce sensor 214 may extend along the rotatable shaft 210 for a distanceat least as great as two adjacent fingers 212, other lengths may becontemplated. For example, the PDE force sensor may extend the entirelength of the rotatable shaft 210. Similar to placing the PDE forcesensor on the ice cube mold 100, the particular length of the PDE sensorimplemented on the rake's shaft 210 may preferably be selected tomeasure the force and deflection on a part of the rake 200 deemed mostlikely to fatigue. In this configuration, the PDE force sensor 214 maydetect an angle of twist greater than 2 degrees along the rotatableshaft 210 indicative of potentially excess motor torque or an impactedice cube.

As shown in FIG. 7, PDE force sensors 216 may be placed on one or moreof the fingers 212 of the rake 200. Consequently, the removal forceapplied to expel each ice cube from a cavity 116 in the ice cube mold100 may be independently monitored. In this way, one of the PDE forcesensors 216 may detect excessive torsion of a particular finger 212indicative of an ice cube stuck in a cavity 116. By determining theparticular cavity 116 where excessive force may be required to expel anice cube, additional actions may be taken. Mitigating actions mayinclude alerting the user or automatically initiating a cleaningprocedure.

FIG. 8 shows a side view of a portion of a refrigerator with a door 20having a ledge 308 on which the ice storage bin 22 may rest and afreezer compartment 12 in which is mounted an ice maker 16. As describedabove, the ice maker 16 may be a twist ice maker or a rotating rake icemaker. The ice maker 16 may further include an output 314 for expellingice cubes that is located above the ice storage bin 22. As shown in FIG.8, the output 314 for expelling ice cubes from the ice maker 16 may belocated above and may not overlie the storage bin 22. The storage bin 22defines an ice cube reservoir 316 that has an opening 318 incommunication with the ice maker output 314 for receiving the ice cubes.Preferably, the opening 318 is located at the top of the storage bin 22.

The base 320 of the ice storage bin 22 may be removably supported on anice storage bin mounting plate 322. When attached to the ice storage binmounting plate 322, the ice storage bin 22 is securely connected to therefrigerator 10. As best seen in FIG. 9, mating of protrusions 324located on the ice storage bin mounting plate 322 with recesses 326 inthe base 320 of the ice storage bin 22 may secure the removableconnection. The protrusions 324 and corresponding recesses 326 may beprovided anywhere along the ice bucket mounting plate 322.

Provided on top of the protrusions 324 and, consequently, below the icestorage bin 22, one or more PDE force sensors 310 may detect the weightof the storage bin 22 including its content when it is placed on the icestorage bin mounting plate 322. The PDE force sensor 310 may experiencea level of compression that correlates with the weight placed on it. Inthis way, the PDE force sensors 310 may output a signal that may becalibrated to indicate the weight of the ice cubes within the ice cubereservoir 316.

Typically, an ice storage bin 22 in a freezer compartment of arefrigerator 10 is designed to maximize the ice cube reservoir 316. Thatis, the storage bin 22 may assume the maximum dimensions of the spaceavailable in the freezer compartment and the ice harvesting process maybe configured to produce ice until the ice cube reservoir 316 completelyfills the storage bin 22. Consequently, for many consumers, the storagebin 22 may hold an undesirable amount of ice that may become stagnantand malodorous or may sublimate from unuse. To avoid the problem of icestaleness, it may be desirable to limit the amount of ice availablebased on an individual consumer's preference.

Therefore, to detect the level of ice storage, the controller 104 incommunication with the PDE force sensor 310 may monitor the ice level bydetermining the weight of the ice storage bin 22 with ice cubes in theice cube reservoir 316. In response to the determined level of ice basedon the PDE force sensor output and a user-defined input stating adesired level of ice, the controller may prevent additional iceharvesting by the ice maker 16. The controller 104 may allow forcontinued ice harvesting once the level of ice storage falls below theconsumer's desired level. For example, upon consumption of ice cubes,the PDE force sensor 310 may continue to output a signal to indicate theweight of the ice cubes. Once the weight falls below the valueassociated with the desired level of ice storage, the controller maysignal the ice maker 16 to continue harvesting. Alternatively, theconsumer may choose to increase the desired level of ice storage.

In addition to preventing an ice harvesting process when the icereservoir 316 reaches a desired level of ice cubes, the ice makingassembly may be designed to prevent ice harvesting when the storage bin22 is removed from the refrigerator 10. As shown in FIG. 8, the PDEsensor 310 may detect when the storage bin 22 is not positioned 328 toreceive ice cubes. Upon detection of a voltage indicative of little orno weight being applied, the PDE sensor 310 may transmit a signal to thecontroller 104. The controller 104 may then prevent the ice maker 16from expelling ice cubes to the storage bin 22.

Depending upon the placement and configuration of the PDE sensor 310 andcontroller 104, it is contemplated that the PDE sensor 310 may beoperated in a wireless configuration. While it is generally known tooperate sensors with either a hard-wired or wireless connection, typicalwireless sensors require external power sources that require additionalwiring to power supplies. As previously described, PDE sensors 310require very little power for operations. Additionally, PDE devices maybe configured to generate power when exposed to mechanical vibrations.That is, PDE devices may scavenge energy from ambient vibrations. Forrefrigerators, sources of mechanical vibration may include a power cycleof the compressor, placement of the ice storage bin 22 onto the icestorage bin mounting bracket 322, the kinetic energy from harvested icelanding in the ice storage bin 22, the weight of products as they areplaced on refrigerator shelves, etc. By either storing scavenged energyinto a battery or using power on demand, the PDE sensor 310 may locallysource power for operating a wireless connection to the controller 104.The PDE force sensor 310 and the energy scavenging PDE device may be thesame device or may be implemented as separate devices. While operatingone or more PDE sensors with a power scavenging PDE device may provide adesirable power saving feature, it is noted that a more typical wiredconnection to enable communication between the PDE sensor 310 and thecontroller 104 may be implemented.

While the invention has been specifically described in connection withcertain specific embodiments thereof, it is to be understood that thisis by way of illustration and not of limitation. Reasonable variationand modification are possible within the scope of the forgoingdisclosure and drawings without departing from the spirit of theinvention which is defined in the appended claims.

What is claimed is:
 1. An ice making assembly comprising: an ice makerhaving an output for expelling ice cubes; a storage bin defining an icecube reservoir and having an opening in communication with the ice makeroutput; and a weight sensor comprising a piezo dielectric elastomer(PDE) provided below the storage bin and outputting a signal indicativeof the weight of the ice cubes within the reservoir; wherein ice cubesexpelled from the ice maker are received through the opening and storedin the ice cube reservoir, with the weight sensor providing an outputindicative of the weight of the ice cubes within the reservoir.
 2. Theice making assembly of claim 1, wherein the ice maker is located higherthan the storage bin.
 3. The ice making assembly of claim 2, wherein theopening is in a top of the storage bin.
 4. The ice making assembly ofclaim 3, wherein the output does not overlie the opening.
 5. The icemaking assembly of claim 1, wherein the weight sensor is attached to astorage bin mounting plate.
 6. The ice making assembly of claim 5,wherein the storage bin is removable from the storage bin mountingplate.
 7. The ice making assembly of claim 5, wherein the storage bincompresses the weight sensor when the storage bin is placed onto thestorage bin mounting plate.
 8. The ice making assembly of claim 1,wherein the ice maker expels ice cubes when the weight sensor output iswithin a pre-specified range.
 9. The ice making assembly of claim 8,wherein the pre-specified range is based in part on a user input. 10.The ice making assembly of claim 9, wherein the user input selects anamount of ice available in the storage bin wherein a selected amount ofice is less than a maximum amount of ice that the storage bin will hold.11. The ice making assembly of claim 1, wherein the ice maker expels icecubes when the weight sensor output is below a pre-specified value. 12.The ice making assembly of claim 1, wherein the ice maker expels icecubes when the weight sensor output is equal to or below a pre-specifiedvalue.
 13. The ice making assembly of claim 1, wherein the ice makerexpels ice cubes when the weight sensor output is above a pre-specifiedvalue.
 14. The ice making assembly of claim 8, wherein the pre-specifiedrange is based in part on a capacity of the storage bin.